LEDs are used in electronic displays, such as liquid crystal displays in laptops or LED televisions. Conventional LED units are fabricated by mounting LEDs to a substrate, encapsulating the mounted LEDs and then optically coupling the encapsulated LEDs to an optical waveguide.
Typically, numerous LEDs are fabricated simultaneously on a single wafer and then the wafer is diced to form individual LEDs. When dicing the individual LEDs from a sapphire substrate, the sapphire substrate is thinned to approximately 100 um and then etched or mechanically scratched to create scribe marks for a subsequent break step using an anvil. Alternatively, the scribe marks may be formed with a laser.
Fabricating individual LEDs using the conventional dicing methods may result in damage to the wafer and the LEDs. For example, a continuous GaN layer on a sapphire substrate imparts a compressive stress on the underlying sapphire substrate which can affect the curvature of the substrate and may lead to undesired breakage of the substrate and destruction of the LEDs on the substrate.